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                        TESTING THE EFFICIENCY
                      OF WOOD-BURNING COOKSTOVES
                      International Standards
                      Originally prepared from
                 proceedings of a meeting of experts
                    convened in December 1982 by
              Volunteers in Technical Assistance (VITA)
                         Revised May 1985
                               Published by:
                  1600 Wilson Boulevard, Suite 500
                    Arlington, Virginia 22209 USA
              Tel:  703/276-1800 . Fax:   703/243-1865
                       ISBN 0-86619-229-8
             (c) 1985, Volunteers in Technical Assistance
Water Boiling Test
    Procedural Notes
    Data and Calculation Form
    Test Series Reporting Form
Controlled Cooking Test  
    Procedural Notes
    Data and Calculation Form
    Test Series Reporting Form
Kitchen Performance Test
    Procedural Notes
    Data and Calculation Form
    Test Series Reporting Form
Technical Notes
     A. Concepts of Efficiency
     B. Participants at Arlington meeting
     C. Participants at Louvain "Woodstoves Seminar"
     D. Participants at Marseille meeting
This document is a revision of Testing the Efficiency of Woodburning
Cookstoves, first published by Volunteers In Technical Assistance in
December, 1982.  The earlier work was the outcome of a special international
workshop held in Arlington, Virginia, through the support of the
U.S. Agency for International Development (USAID), the Government of The
Netherlands, and IBM/Europe.   Since publication, many useful comments
have been received from users of this document, enabling us now to
clarify a number of concepts and remove certain inconsistencies.  In some
cases we have rejected suggestions that would have demanded a revision
of fundamental principles agreed to at Arlington.   Such changes were felt
to go beyond the scope of this work.
These revised guidelines are an effort to bring the work of the
Arlington Group to a wider audience for practice, scrutiny and further
discussion.  We hope that such a process will lead to an even more
refined version of procedures for testing woodburning cookstoves.
                       Paul Bussman, The Woodburning Stove Group,
                       Eindhoven, The Netherlands
                       Jonathon Loose, Intermediate Technology Development
                       Group, Reading, England
                       K. Krishna Prasad, The Woodburning Stove Group,
                       Eindhoven, The Netherlands
                       Timothy Wood, Volunteers in Technical Assistance,
                       Arlington, Virginia, USA
                                             February, 1985
Testing is an essential component of any program that promotes the use        
of improved woodburning stoves in developing countries.   This is true
regardless of how programs are administered or by what means the stoves
are disseminated.
Stove testing is the systematic measuring of the advantages and limitations
of a particular stove model.   Its primary aim is to help identify
the most effective and desirable stoves for a specific social and economic
context.  With ongoing stove production, a testing program provides
essential quality control and may lead to important design modifications.
Problems surrounding woodstove design and testing have gained increasing
attention over the past several years.   Many individuals and groups have
become involved, circulating papers, and meeting occasionally to discuss
problems.  At the "Seventh Woodstove Seminar" held at Louvain, Belgium,
March 4 - 5, 1982, it was agreed that a systematic effort should be
undertaken to reach as wide a consensus as possible on field testing of
woodstoves.  Too many approaches to testing were being used, it was felt,
resulting in misunderstanding and hindering comparison of results.
An informal international working group of Louvain participants and
others on developing a standard for field testing of woodstoves met in
Marseille 12 - 14 May, 1982.   This group agreed that there was an urgent
need for an internationally acceptable standard.   It noted that field
testing had been done in many places by many different people, some of
whom have published on the subject and made suggestions for standards.
None of the published suggestions was used as a basis for discussion.
Rather, the group brainstormed from comments received following the Louvain
meeting, and from new ideas, keeping the earlier suggestions in
The consensus at Marseille was that:
* A worldwide standard should be simple and limited. A standard will be
  more acceptable if it imposes strict rules only where necessary, but
  includes recommendations where possible.
* A distinction should be made between testing done for local use only
  (for stove users and others) and testing where the results are intended
  to be transmitted to other places.
* The standard should represent a compromise between the widest possible
  range of applications, and the closest possible fit with actual cooking
* It would be useful for the standard to classify the many different
  parameters that influence stove performance.
The Marseille group decided that evaluation concepts and reporting specifications
could be fixed in the standard test procedure, and that
food, fuels, and pots could be specified in local standards.  While the
stove itself cannot be standardized, a detailed description of the stove
is needed with the test report.   It was thought that an international
standard might recommend a way to do this.   Discussions resulted in a set
of "instructions" for the draft of a proposed standard.  The Marseille
group draft was circulated among participants, who then provided comments.
The resulting second draft was discussed, among others, at the
meeting convened by VITA December 6 - 10, 1982.
The 13 stove experts from ten countries who attended the week-long
Arlington meeting agreed on three basic tests and reporting procedures.
By imposing a scientific standard in stove testing, the Arlington group
hopes to assure a high degree of uniformity in stove test results from
around the world.  The widespread use of standardized testing procedures
will permit the comparison of stove designs on a more systematic basis,
and foster wider sharing of the results of research and development
efforts.  This will benefit stove designers and users, and ultimately all
who depend on the world's forest resources.
The following tests were formulated by the group at Arlington:
A Water boiling test, to measure how much wood is used to boil water
under fixed conditions.  This is a laboratory test, to be done both at
full heat and at a lower "simmering" level to replicate the two most
common cooking tasks.  While it does not necessarily correlate to actual
stove performance when cooking food, it facilitates the comparison of
stoves under controlled conditions with relatively few cultural variables.
A Kitchen performance test, to measure how much fuelwood is used per
person in actual households when cooking with a traditional stove, and
when using an experimental Stove.   The tester simply measures how much
wood the family has at the beginning and at the end of each testing
A controlled cooking test, to serve as a bridge between the water boiling
test and the kitchen performance tests.   Trained local cooks prepare
pre-determined meals in a specified way, using both traditional and
experimental stoves.
The Arlington group recognized that some of the procedures described
here differ significantly from what had been recommended in the past.
The main difference is in the concept of efficiency used.  These standards
are based on a broader description and justification of efficiency
than Percentage of Heat Utilized (PHU).   They interpret evaporation as a
measure of energy wasted, not energy used (see Appendix A, Concepts of
Efficiency).  It is not the group's intention to demand that these standards
be adopted.  Rather, it is hoped that stove testers will use the
standards and share their experience in using them.   The purpose of
developing standards for testing is to help technicians get the most
reliable results from their tests, to consider sources of error, and to
interpret test results reliably.   These standards do not preclude the use
of existing ways of testing; however, the group thinks that the new
standards can yield more reliable, comparable results.
This document includes the step by step procedures for each of the standardized
tests, followed by Procedural Notes that give specific suggestions
for conducting the tests.  The sample data and reporting forms
included for each test are designed to simplify the recording of essential
information.  For easy reference, Technical Notes giving background
information relevant to all three tests are printed on colored paper.  A
glossary and list of abbreviations are followed by a section discussing
concepts of efficiency used in testing stoves.
The original document was prepared by Dr. Timothy Wood, with Prof. Guido
de Lepeleire, Dr. Gautam Dutt, and Howard Geller.   Editing was done by
Margaret Crouch, with typesetting by Maria Garth.   The Arlington meeting
was made possible by the support of the U.S. Agency for International
Development (USAID), the Government of the Netherlands, and IBM/Europe.
USAID also funded this revised edition of the manual.   A complete list of
the participants in the Arlington meeting is included in the Appendix.
                    WATER BOILING TEST
The Water Boiling Test (WBT) is a relatively short, simple simulation of
common cooking procedures.  It measures the fuel consumed for a certain
class of tasks.  It is used for a quick comparison of the performance of
different stoves.
Water Boiling Tests use water to simulate food; the standard quantity is
two-thirds the full pan capacity.
The test includes "high power" and "low power" phases.  The high power
phase involves heating the standard quantity of water from the ambient
temperature to boiling as rapidly as possible.   (see Technical Note 1).
The low power phase follows.   The power is reduced to the lowest level
needed to keep the water simmering over a one-hour period.
Each WBT should be repeated at least four times.   Results may be averaged
and analyzed statistically.
* Stove
* Pots without lids - see Procedural Note 1)
* A balance accurate to 10 grams with a recommended capacity of 5 kg
  (Technical Note 2)
* Locally dominant wood species, air dried (Technical Notes 3, 4), preferably
  pieces of uniform size
* Water, within 2 [degrees] C of ambient temperature
* Timing device
* Mercury or digital thermometer for measuring temperatures up to 105 [degrees] C
  (Technical Note 6)
* Device to measure/estimate the moisture content of wood (Technical
  Note 4)
* Forms for recording data and calculations
* Optional:  wire tongs for handling hot charcoal and wood; insulated
1. Determine and record moisture content for wood to be used in test.
   See Technical Notes 3 and 4, pp. (Note:  this is generally done for a
   series of tests, rather than for each individual test.)
2. Note and record the test conditions.   Prepare a drawing of the pots
   and stove to be tested.  (Note:   in any test series be sure to use the
   same pots for all tests.)  Include all relevant stove dimensions and
   show how the pots fit into the stove (Technical Note 9).  Note climatic
   conditions (Technical Note 8).
3. Weigh the empty, dry pots, and record this weight on the Data and
   Calculation Form.  Fill each pot with water to 2/3 capacity and record
   the new weight.
4. Take a quantity of wood not more than twice the estimated needed
   amount, weigh it, and record the weight on the Data and Calculation
5. Place a thermometer in each pot so that water temperature may be
   measured in the center, about 1 cm from the bottom.  Record water
   temperatures and confirm that they vary no more than 2 [degrees] C from
6. After a final check of preparations, light the fire as in Technical
   Note 10.   Record the exact starting time.   Throughout the following
   "high power" phase of the test, control the fire with the means
   commonly used locally to bring the first pot to a boil as rapidly as
7. Regularly record the following on the Data and Calculation Form:
   * the water temperature in each pot;
   * the weight of any wood added to the fire;
   * any action taken to control the fire (dampers, blowing, etc.); and
   * the fire reaction (smoke, etc.).
8. Record the time at which the water in the first pot comes to a full
9.  At this time rapidly do the following:
    * Remove all wood from the stove and knock off any charcoal.  Weigh
      the wood, together with the unused wood from the previously
      weighed supply.
    * Weigh all charcoal separately (Procedural Note 2).
    * Record the water temperature from each pot.
    * Weigh each pot, with its water.
    * Return charcoal, burning wood, and pots to the stove to begin the
      "low power" phase of the test.
    Record all measurements on the Data and Calculation Form.
    With practice a single tester can complete this step within 2 to 4
    minutes and move on to Step 10 without introducing significant error
    to the data.   If, however, this interruption is judged too difficult
    or disruptive, an alternate procedure is suggested in Procedural
    Note 3.
10. For the next 30 minutes maintain the fire at a level just sufficient
    to keep the water simmering.  Use the least amount of wood possible,
    and avoid vigorous boiling.  Continue to monitor all conditions noted
    in Step 7.   If the temperature of the water in the first pot drops
    more than 5 [degrees] below boiling, the test must be considered invalid.
11. Recover and weigh separately the charcoal and all remaining wood.
    Record the weights.
12. Weigh each pot with its remaining water.   Record the weight.
13. Calculate the amount of wood consumed, the amount of water remaining,
    the test duration, the Specific Fuel Consumption, and, for
    multipot stoves, the Consumption Ratio (Procedural Note 5).  Minimum
    and maximum power levels may also be calculated (Technical Note 11).
14. Interpret test results (see Procedural Note 4), and fill out a Test
    Series Reporting Form.
1.  Stove tests are often conducted with lidded pots to reduce the effect
    of drafts on evaporation rate from the pot.  However, if the
    testing site is properly protected from drafts, lids should be left
    off, thus reducing the error caused by condensed water dripping from
    the lid back into the pot.
2.  With lightweight stove models, often the stove and its contents can
    be weighed together as a unit, and the weight of the empty stove
    subtracted later.  It is not necessary to separate charcoal and
    ashes, since ash weight is usually insignificant.
3.  "High power" and "low power" tests may be conducted separately.   The
    fire is extinguished at the end of Step 7, and the stove is allowed
    to cool.   The entire test is then repeated in exactly the same way,
    except that the fire is reduced the moment the first pot comes to a
    boil.   There is no interruption to weigh water or fuel as described
    in Steps 8-13.
    The test is ended 30 minutes after boiling, and all measurements are
    recorded.   The weight of the fuel used during the high power phase is
    subtracted from the total amount used in the low power phase.  A separate
    or modified data sheet is needed for recording test results.
    Final calculations remain unchanged.
4.  It is important to know how to interpret the results of the WBT, and
    to remember that a low specific fuel consumption indicates a high
    efficiency.   As efficiency declines, Specific Fuel Consumption (SFC)
    rises.   It is possible to use WBT results to judge the suitability of
    a stove for various cooking tasks.  For example, for high power cooking
    (rapid frying and boiling), a stove with the greatest high power
    efficiency might be best; for simmering, however, the best stove
    might be the one that shows low SFC for both high and low power.
    (See also Appendix A which explains concepts of efficiency.
5.  The Consumption Ratio may be useful when testing stoves that accommodate
    more than one pot.  It expresses the amount of water evaporated
    from the main pot as a fraction of the total evaporated from
    all pots.
The consumption ratio is always less than 1.0.   The lower its value,
the lower the proportion of heat used by the main pot.
There are at least two ways in which the Consumption Ratio may be
useful to the stove tester:
a) It serves as a check on consistent stove operation.   With multipot
   stoves the user determines how heat from the fire is apportioned
   to the various pots.  In a series of Water Boiling Tests it is
   essential that this be done in a consistent manner.  By comparing
   the Consumption Ratios in a test series one can detect variations
   in stove operation.
b) It may help to show whether enough heat reaches all the pots to
   be useful for cooking.
As a rule, Consumption Ratio should not be used as a correction
factor for comparison of multipot and singlepot stoves.   Such comparisons
are never valid in Water Boiling Tests because of the many
interfering variables.
                                      WATER BOILING TEST
                                  DATA AND CALCULATION FORM(*)
Test Number_______________         Location_________________________________________
Date______________________         Test conditions__________________________________
Stove_____________________         Remarks___________________________________________
Tester____________________         __________________________________________________
                                                             END OF                      END OF
                                   INITIAL                 HIGH POWER                  LOW POWER
                                 MEASUREMENT                  PHASE                        PHASE
Wood moisture content        a) ____________
Dry weight of Pot #1         b) ____________
Dry weight of Pot #2         c) ____________
Weight of wood               d) ____________kg           j) ___________kg           s) ____________kg
Weight of charcoal                                        k) ___________kg            t) ____________kg
Weight of Pot #1 with water  e) ____________kg           m) ___________kg           u) ____________kg
Weight of Pot #2 with water  f) ____________kg           n) ___________kg           v) ____________kg
Water temperature, Pot #1    g) ____________[degree] C   p) ___________[degree] C   w) ____________[degree] C
Water temperature, Pot #2    h)             [degree] C    q) ___________[degree] C    y) ____________[degree] C
Time                         i) ____________             r) ___________             z) ____________
(Use the graph outline on reverse side to record changes in water temperature)
CALCULATIONS                 HIGH POWER PHASE                   LOW POWER PHASE
Wood consumed                    A) d-j = ______________ kg      J) j-s = _________________ kg
Charcoal remaining               B) K = ________________ kg      K) t-k = _________________ kg
Equivalent dry wood consumed     C) A/(1+a)-1.5 B = ____ kg     L) J/(1+a)-1.5 K = _______ kg
Water vaporized, Pot, #1         D) e-m = ______________ kg      M) m-u = _________________ kg
Water vaporized, Pot #2          E) f-n = ______________ kg      N) n-v = _________________ kg
Consumption ratio                F) D/(D+E) = _____________      P) M/(M+N) = ________________
Specific fuel consumption        G) C/D = _________________      Q) L/M = ____________________
Duration of test                 H) r-i = _________________      R) z-r = ____________________
Burning rate                     I) C/H = ____________kg/min     S) L/R = ______________kg/min
                  Overall Specific Fuel Consumption (SFC):  (C+L)/(D+M) = ____________
(*) This is an example of a form to be completed every time a test is run.
    It is easily modified for cases where high and high-low power phases are run independently.

44p08.gif (600x600)

                              WATER BOILING TEST
                          TEST SERIES REPORTING FORM
Organization conducting tests _________________________________________________
   Mailing address ____________________________________________________________
Name of stove tested __________________________________________________________
Test numbers being reported ___________________ Test supervisor _______________
SUMMARY OF TEST CONDITIONS (draft protection, ambient temperature, etc.)
     SPECIES               APPROX % TOTAL          MOISTURE            MEAN DIMENSIONS
  (Botanic name)             (by weight)           CONTENT
  _______________         __________ Kg          _________ %        _______________
  _______________          __________ kg           _________ %         _______________
  _______________         __________ kg          _________ %        _______________
  _______________         __________ kg          _________ %        _______________
                           POT 1         POT 2              POT 3
  Weight (empty, dry)  ________ kg      _________ kg        _______ kg
  Maximum capacity     ______ liters    _______ liters      ______ liters
  Diameter at rim      ________ cm      _________ cm        _________ cm
  Composition           ____________     ______________      _____________
               HIGH POWER PHASE               LOW POWER PHASE
  TEST       BURNING RATE       SFC           BURNING RATE       SFC     OVERALL
   NO.         (kg/min)                         (kg/min)                    SFC
    1       _____________       ____          ____________      ____      _________
    2       _____________       ____          ____________      ____      _________
    3       _____________       ____          ____________      ____      _________
    4       _____________       ____          ____________      ____      _________   
    5       _____________       ____          ____________      ____      _________      
                      (Full description of stove on reverse side)
(*) This is an example of a form to summarize and report results from a series of
    water boiling tests.  It is easily modified for cases where high and high-low
    power phases are run independently.
TOP VIEW                                      PERSPECTIVE
CUTAWAY VIEW WITH POT(S)                      FRONT
DETAILS OF STOVE CONSTRUCTION _________________________________________________
                      CONTROLLED COOKING TEST
The Controlled Cooking Test is intermediate to the rather simple Water
Boiling Test and the involved Kitchen Performance Test.   It is intended
to provide estimates of the fuel consumed by a set of specified cooking
Unlike the Water Boiling Tests with its rigidly fixed procedures, the
Controlled Cooking Tests uses variable procedures depending on the types
of meals cooked, the stove design, and the manner in which the stove is
used.  Results of Controlled Cooking Tests are comparable only when conducted
in the same series using exactly the same procedures and conditions.
The primary objectives of the Controlled Cooking Test (CCT) are:
* To compare the fuel consumed and the time spent in cooking a meal on
  different stoves; and
* To determine whether a stove can effectively cook the range of meals
  normally prepared in the area where it is intended to be introduced.
The Controlled Cooking Test may also be used:
* To compare different cooking practices on the same stove,,
* To give a cook the opportunity to learn how to use the stove; and
* To follow the Water Boiling Test in subjecting a stove to more realistic,
  but controlled, conditions.
The CCT is normally conducted in a laboratory or field demonstration
center by trained stove testers with extension workers or potential
users.  The cook should be experienced in preparing traditional meals.
* A homogeneous mix of fuelwood as it is normally available locally,
  sufficient for the required number of tests (see Technical Note 5).
* A selected type and amount of food sufficient for the required number
  of tests.
* Weighing instrument accurate to 10 grams, with a recommended capacity
  of 5 to 10 kg, depending on the amount of food prepared in each test
  (Technical Note 2).
* Timing device.
* The same pots, lids, and other cooking utensils to be used throughout
  the test.
* Forms for recording data and calculations.
* Optional:  wire tongs for handling hot charcoal and wood; insulated
1.  Establish a test design that accurately represents common local
    cooking procedures.   (Procedural Note 1).  It is advisable to test
    both new and traditional stoves simultaneously under the same weather
    conditions and using wood of similar quality and condition.
2.  Remove any charcoal and ash from the stove to be tested.  The stove
    should not be warm from a previous fire.
3.  Record climatic conditions (Technical Note 8).
4.  Take a quantity of wood not more than twice the estimated amount
    needed measure moisture content (Technical Notes 3, 4).  Weigh it and
    record the weight on the Data and Calculation Form.
5.  Weigh the pots with their lids (if lids are normally used) and record
    the weight.
6.  Assemble, prepare and weigh the food to be cooked.
7.  Light the fire and record the time (Technical Note 10).
8.  Perform the defined cooking task.
9.  When the cooking task is completed, record the time (Procedural
    Note 2).
10. Weigh separately the remaining wood and charcoal.
11. Weigh the food in its pots, including any lids.
12. Record comments from the cook on any problems encountered during the
    test, including qualitative differences between the tested stove and
    other stoves.
13. Repeat the same test at least three times for each type of meal
    cooked.   More tests may be required if there is much variation in the
14. For each test calculate total test time and Specific Fuel Consumption.
    Then write a test report for each test using, if desired, the
    sample Data and Calculation Form on the following page.  Include a
    description of:
    * stoves and pots used in the test (Technical Note 9);
    * standard meal used in the test; and
    * standard procedure used to cook the meal.
1.  The CCT design is tailored to specific local meals.  It is therefore
    important to specify the following conditions:
    *   Pot types and sizes.
    *   Fuelwood types and sizes.
    *   One or two standard meals commonly prepared in the region.  Where
       several types of meals are prepared, select no more than two for
       the test, one requiring long cooking time and the other short.
    *   Exact cooking tasks and sequences required to cook the standard
       meal.   For example:   "Bring the first pot to a boil; switch the
       first and second pots; bring the second pot to a boil; reduce the
       fire by breaking off charred ends of fuel; remove the first pot
       and simmer the second until the food is cooked."
    Establishing the test design may be done in either of two ways:  1.)
    by conducting a thorough survey of local cooking practices to collect
    the needed information; 2.)  by having a team of three to five
    experienced local cooks define the one or two standard meals and the
    specific way they should be prepared and cooked for the test.
2.  It is important to consider the criteria by which food will be considered
    "done," since this determines the time at which the tests
    will be finished.  It is best to determine the time objectively, such
    as "The skins come off the beans," or "The porridge loses all traces
    of graininess."  However, even if the criteria used are very subjective
    ("The sauce tastes right"), they should still be mentioned in
    the test design.  Whatever the criteria used, the cook must be encouraged
    to be very consistent in judgement.
3.  Often the stove with its contents can be weighed together as a unit,
    and the weight of the empty stove subtracted later.  It is not necessary
    to separate charcoal and ashes, since ash weight is usually insignificant.
                             CONTROLLED COOKING TEST
                           DATA AND CALCULATION FORM(*)
Test Number ______________     Location ___________________________________
Date _____________________     Test conditions ____________________________
Stove ____________________     Remarks ____________________________________
Cook _____________________     ____________________________________________     
                               INITIAL              FINAL
 Weight of wood               (A)________kg       (G)________kg
 Weight of charcoal                             (H)________kg
 Wt of Pot 1   (empty)         (B)________kg      (I)________kg   (with cooked food)
 Wt of Pot 2   (empty)         (C)________kg      (J)________kg  (with cooked food)
 Wt of Pot 3   (empty)         (D)________kg      (K)________kg  (with cooked food)
 Time                         (E)__________       (L)__________
 Wood moisture content       (F)__________
      (M) Weight of wood used          A-G =              _________kg
      (N) Equivalent dry wood used     M/(1+F)-1.5 H =    _________kg
      (P) Weight food cooked, Pot 1    I-B =              _________kg
      (Q) Weight food cooked, Pot 2    J-C =              _________kg
      (R) Weight food cooked, Pot 3    K-D =              _________kg
      (S) Total weight food cooked     P+Q+R =            _________kg
      (T) Specific fuel consumption    N/S =              _________
      (U) Total testing time           L-E =              ________min
Cook's comments about stove performance, ease of use, etc.:
(*) This is an example of a form to be used for each test that is run.
                             CONTROLLED COOKING TEST
                           DATA AND CALCULATION FORM(*)
Test Number ______________     Location ___________________________________
Date _____________________     Test conditions ____________________________
Stove ____________________     Remarks ____________________________________
Cook _____________________     ____________________________________________     
                               INITIAL              FINAL
 Weight of wood               (A)________kg       (G)________kg
 Weight of charcoal                             (H)________kg
 Wt of Pot 1   (empty)         (B)________kg      (I)________kg  (with cooked food)
 Wt of Pot 2   (empty)         (C)________kg      (J)________kg  (with cooked food)
 Wt of Pot 3   (empty)         (D)________kg      (K)________kg  (with cooked food)
 Time                         (E)__________       (L)__________
 Wood moisture content       (F)__________
      (M) Weight of wood used          A-G =              _________kg
      (N) Equivalent dry wood used     M/(1+F)-1.5 H =    _________kg
      (P) Weight food cooked, Pot 1    I-B =              _________kg
      (Q) Weight food cooked, Pot 2    J-C =              _________kg
      (R) Weight food cooked, Pot 3    K-D =              _________kg
      (S) Total weight food cooked     P+Q+R =            _________kg
      (T) Specific fuel consumption    N/S =              _________
      (U) Total testing time           L-E =              ________min
Cook's comments about stove performance, ease of use, etc.:
(*) This is an example of a form to be used for each test that is run.
CCT Series Reporting Form (continued)
Defined procedures for cooking the meal. _____________________________________
Summary of cook's comments, Stove #1__________________________________________
Summary of cook's comments, Stove #2__________________________________________
                       KITCHEN PERFORMANCE TEST
The Kitchen Performance Test (KPT) measures the relative rate of fuelwood
consumed by two stoves as they are used in the normal household
environment.  It is a prolonged test conducted with the willing cooperation
of individual families.  Compared to the previously described tests,
the results of the KPT can provide the most reliable indication of stove
performance under actual household conditions.   However, because of the
large effort involved, it is normally conducted only after the more controlled
tests have been completed.
The primary objectives of the KPT are:
  * To study the impact of a new stove on overall household energy use
    (Procedural Note 1); and
  * To demonstrate to potential users the fuel-saving quality of a new
    stove in the household, and to specific correct operating practices.
Variations of the Kitchen Performance Test may also be used in conjunction
with a stove dissemination program (Procedural Note 2) or as part
of a survey of household energy use (Procedural Note 3).
Kitchen Performance Tests should be carried out by an investigator who
is accustomed to following instructions, is motivated to do so, and has
certain basic numerical skills.
* Balance for weighing fuelwood.   (Technical Note 2)
* Forms for recording data and calculations
* Pots, etc., to be supplied by household
1.  Select households to participate in the test (Procedural Note 4).
    Explain to family members the purpose of the test, and arrange to
    measure their fuelwood each day.  Encourage the family to use only a
    single stove throughout the testing period.
2.  Gather any needed information about each participating household.
    For example:   determine the sex and age of each person served meals,
    and use this information to calculate the number of standard adult
    persons served (Procedural Note 5); ask about the approximate cost
    of the fuelwood used, in terms of either money spent or time needed
    to collect it; and collect any other information that may help
    interpret the final data (Procedural Note 6).
3.  Define an inventory area for fuel consumption measurement.   Any fuel
    entering or leaving this area must be accounted for (Procedural Note
    7).   Weigh all wood and other fuels in the inventory area.  Estimate
    or measure the moisture content of the wood (Technical Note 4).
4.  Define the testing period of seven consecutive days.  If it is not
    possible to measure for seven days, measure for at least five days.
    Stop and start at the same hour each day (Procedural Note 8).
5.  Visit the household at least daily, if possible, without being
    intrusive.   Weigh wood remaining in the inventory area, and add to
    it if necessary.  Inquire about the number of people being served
    each day, and confirm that the stove is operating properly.
6.  Compile the results at the end of eight days.  Calculate specific
    daily consumption for each household, and then the mean and standard
    deviation (Technical Note 12).  Compare the results with those from
    households using other stoves.
7.  Inform participating families of the results, and thank them for
    their cooperation.
1.  The introduction of a new stove may alter the amount and type of
    cooking done in the household.  For example, the result may be a substantial
    improvement in the well-being of the family, but make little
    change in overall fuel use.  Or it may be that a fire enclosed
    within the stove provides so little light that it becomes necessary
    to use a kerosene lamp.
2.  It may be tempting to use the results of the KPT to estimate the
    fuel saving potential of a new stove before it is widely accepted
    and used.   For this purpose, however, the test would have to be
    greatly expanded to include:
    * many more households, carefully selected to be representative of
      the regional population;
    * a period of time that includes all major seasons;
    * a study of stove deterioration rates and repair records; and
    * an economic analysis demonstrating the economic attractiveness of
      the stove to both the user and the producer.
3.  A survey of cooking practices to determine current local cooking
    procedures, foods cooked and eaten, types of stoves used, etc., is a
    useful starting point for the development and dissemination of
    improved cook stoves.  The survey may be accompanied in a number of
    households by a measurement of all the fuel used for cooking, such
    as is involved in the Kitchen Performance Test.
    Later, new stoves can be introduced into these same households, and
    another KPT may be carried out after the households have had an
    opportunity to get acquainted with the new stoves.  At that time the
    KPT may be accompanied by a user survey to determine how well the
    stoves are being received, with later surveys to evaluate other
    parameters such as stove durability.  Later KPTs may be performed to
    evaluate whether the fuel savings have remained the same and if
    other factors have had a positive or negative influence on the
    stove's long-term acceptability.
4.  For meaningful results:
    * Households should be selected from approximately the same economic
      level.   This will reduce variation and permit more reliable interpretation
      of the results.
    * Participating families should use fuelwood for at least 90 percent
      of their household cooking needs.
    * A minimum of five participating households is essential.  Depending
      on the expected difference in fuel use between the two stoves
      tested, a larger number of households may be necessary.
5.  For purposes of this test, the "standard adult" will be defined
    according to a simplified version of the widely used League of
    Nations formula as shown in Table I.  (Guidelines for Woodfuel
    Surveys, for F.A.O. by Keith Openshaw).
                                     TABLE I
                 "Standard adult" defined in terms of sex and age
                                                Fraction of
                 Sex and age                  standard adult
                 Child, 0-14 years                  0.5
                 Female, over 14 years              0.8
                 Male, 15-59 years                   1.0
                 Male, over 59 years                0.8
6.  Other information gathered for each family may include:
    * the number and types of any other stoves used regularly (for
      making tea, heating water, cooking manioc, etc.);
    * the major activity of the head of the household (a possible indication
      of family economic level);
    * easily observable indicators of social or economic status;
    * uses made of fuelwood other than for cooking food; and
    * tribal or cultural affiliation.
7.  It is recommended that no more fuel be in the inventory area than is
    likely to be consumed during the one-week test period.  If much more
    fuel is stored than will be used, define a smaller inventory area
    from which all fuel for the test is taken.  Stress to household members
    that only wood from the small area be used during the test, and
    that if more wood is needed, the investigator should be present when
    it is added to the pile.  The number of visits the investigator must
    make to the household to weigh the wood will depend on the size and
    adequacy of the initial inventory.
8.  The recommended seven-consecutive-day test period recognizes that
    many family activities are conducted according to a weekly routine.
    Seven days is the shortest time likely to include market days, work
    days, and any weekly religious observances in their proper proportion.
    It often happens that the person conducting the test is unwilling to
    work on the day of weekly religious observance.  In such a case,
    advance provision should be made for a substitute on that day, if
    Note that a seven-day test usually requires eight days of measurement
    (see Data and Calculation Reporting Form on the following
    page).   Similarly, if only a five-day test is planned, measurements
    will be taken for six days.
9.  Different types and sizes of wood used by different households may
    introduce unwanted variation to test results.  To avoid this, the
    tester may consider providing uniform fuelwood to be used for the
    duration of the test.  It is important, however, that this practice
    not encourage the household to use significantly more or less wood
    than it would normally.
                              KITCHEN PERFORMANCE TEST
                            DATA AND CALCULATION FORM(*)
Household No. __________    Family Name __________________________________
Location _________________________________________________________________
                                   STANDARD ADULT
Children 0-14 years _______  x 0.5 = _________     ___________________________
Women over 14 years _______  x 0.8 = _________     ___________________________
Men aged 15-59 yrs. _______  x 1.0 = _________     ___________________________
Men over 59 years   _______  x 0.8 = _________      ___________________________
      (A) TOTAL ADULT EQUIVALENTS:   _________      ___________________________
       SPECIES           APPROX. % TOTAL        MEAN           MEAN
  (Botanic name)         (by weight)           LENGTH        DIAMETER
__________________        ________           ______cm        ______cm
__________________        ________           ______cm        ______cm                            
__________________        ________           ______cm        ______cm                            
Condition of fuelwood:  (dry / damp / wet / green)_______________________
Fuelwood cost per kg: ________________________ OR ____________ = $_______
                      estimated collection time   local currency US dollars
                              DESCRIPTION                 FUNCTION
Other fuels in use:  ________________________    ___________________________  
                     ________________________    ___________________________
Other stoves in use: ________________________     ___________________________
                     ________________________    ___________________________
Day  0       (None)  kg         _________kg      ______________________________    
Day  1      _________kg          _________kg     ______________________________
Day  2      _________kg          _________kg     ______________________________
Day  3      _________kg          _________kg     ______________________________
Day  4      _________kg          _________kg     ______________________________
Day  5      _________kg          _________kg     ______________________________
Day  6      _________kg          _________kg     ______________________________
Day  7 (B) _________kg         (None)    kg     _____________________________
 (D) TOTAL WOOD CONSUMED:  C-B =     ________kg
 (E) TEST DURATION:         _____________ days
(*) This is an example of a form to be used for each participating household.
                      KITCHEN PERFORMANCE TEST
                   TEST SERIES REPORTING FORM(*)
Organization conducting tests ______________________________________________
Names of stoves compared: (1) ______________________   (2) __________________
Testing location ___________________________________________________________
Testing period   ___________________________ Names of test supervisor ______                        Name of test supervisor
                   (months)     (year)
                             STANDARD ADULT    SPECIFIC DAILY    FUELWOOD
                              EQUIVALENTS       CONSUMPTION      COST / KG
  ARITHMETIC MEAN:            ____________       ___________       _________
  STANDARD DEVIATION:         ____________       ___________       _________
  COEFFICIENT OF VARIATION:   ____________       ___________       _________
  STANDARD ERROR               ____________      ___________      _________
  95% CONFIDENCE INTERVAL:    ____________       ___________       _________
  ARITHMETIC MEAN             _____________     _____________       _________
  STANDARD DEVIATION:         _____________     _____________      _________
  COEFFICIENT OF VARIATION:   _____________     _____________       _________
  STANDARD ERROR:             _____________     _____________       _________
  95% CONFIDENCE INTERVAL:    _____________     _____________       _________
                              (TOTAL NUMBER OF TESTS ________________)
Specific Daily Consumption:  t-Value= _____  at   ______  % level of confidence
       and   ______ degrees of freedom.
       (Attach a full description of both stove models tested)
(*) This is an example of a form used to summarize and report results from
      a series of tests of two stoves being compared.
                TESTING PROCEDURES
1.  Atmospheric pressure and boiling temperature
The normal boiling temperature of water depends on atmospheric pressure,
which is mainly a function of altitude above sea level.   At an
altitude ((H)) the normal boiling temperature can be computed from
                 [T.sub.b] = (100 - H/300) [degrees] C
when H is expressed in meters.   For example, the normal boiling point
is 100 [degrees] C at sea level, and 95 [degrees] C at 1500 m altitude.
When comparing high-power WBT results from different places this can
be taken into account by using a simple temperature factor:
                         W" = W'([T.sub.b] - [T.sub.o])/100
where W" is the corrected amount of water processed, [W.sub.o] is the weighed
quantity of water, and [T.sub.o] is the starting temperature.  The reference
temperature difference is considered to be 100 [degrees] C.
Note that cooking times increase with reduced boiling temperatures at
high altitudes.  The cooking time is doubled for a temperature decrease
of 5 [degrees] to 10 [degrees] C, depending on the kind of food.  This may influence
Kitchen Performance Test results, but not Water Boiling Tests.
2.  Weight (mass)
Weighing can be done with any good balance that is accurate to a minimum
1 percent of the full-scale reading.   For field testing, direct
reading instruments are preferable, as no adjustments of weights are
needed.  Spring balances do a good job if they have a long reading
scale and thus good resolution, and if they are used within 20 to 100
percent of the full capacity.   Spring balances should occasionally be
checked with calibrated weights (1 liter of water weighs 1 kg, etc.)  A
set of balances with different full-scale capacities should be used;
for example, 1, 5, and 15 kg.   Compare them with each other:  they
should give the same reading for the same load.
The weighing basket used with a balance should be as light as possible,
since precision is lost when the difference between two weighings
is relatively small.
3.  Moisture content of wood.
The available heating energy of fuelwood is directly influenced by its
moisture content. This is usually expressed on the basis of dry wood,
according to
                              mass of moisture in wood sample
       Moisture content (x) = _______________________________
                              mass of oven-dry wood sample
Thus the heating value of moist wood, [H.sub.x], can be calculated from the
heating value of oven-dry wood, [H.sub.o], by
                                              [H.sub.o]                                 [H.sub.x] -  _______      Ho
                                [H.sub.x] -    ________ (*)
                                              1 + x
So-called "air-dried" wood is, in fact, moist.  Its moisture content
varies with the average relative humidity and with the species of
For example, in saturated air (RH = 1), 1.0 kg of dry wood will
contain about 0.2 kg of water (possibly more).   At a lower RH = 0.6,
the moisture content X drops to about 0.12.   Of course, RH and X can be
expressed as percentages as well.
As a consequence, a larger quantity of moist wood [M.sub.x] is needed for a
given job than of dry wood [M.sub.o].   This can be accounted for by computing
an equivalent dry wood consumption from a measured moist wood quantity.
          (equiv. dry wood) [M.sub.o] = (1 - X) . [M.sub.x] (moist wood)
(*) This is an approximate formula.   For a more exact formula, see K.
    Krishna Prasad, "Wood-burning Stoves:  Their Technology, Economics,
    and Deployment," Working Paper for World Employment Programme
    Research, International Labour Organization, Geneva, 1983.
4.  Moisture measurements
The moisture content (X) of air-dried firewood can be estimated from
the humidity RH (See Technical Note 3) (X = 0.2 RH).
The most direct and precise procedure is to make a double weighing of
a moist or air-dried sample:   first as it is, and then after drying it
in an oven (at 110 [degrees] C for 24 hours or more, depending on the sample
size). With [M.sub.x] (moist weight) and [M.sub.o] (dry weight):
The precise weight of the wood sample can be recorded periodically.
When there is no change in two successive weighings the sample is
presumed to be oven-dry and its new weight, [M.sub.x], is recorded.  The moisture
content of the original sample is then given by
                      X = ([M.sub.x] - [M.sub.o]/[M.sub.o]
where [M.sub.x] is moist weight and [M.sub.o] is oven-dry weight.
When a commercial drying oven is not available, it is possible to
construct a simple substitute using electric light bulbs.  For a
description, see the article by Bill Stewart in Boiling Point,
published by Intermediate Technology Development Group, April 1984.
An alternative method to determine moisture content is by use of a
battery-powered moisture meter.   These devices work on the principle
that electrical conductivity of the wood varies with its moisture
content.  The results depend slightly on the species of wood and the
quality of the instrument used.   Generally they detect as little as X <
5.  Fuelwood variation
Different types, sizes, and conditions of fuelwood are a potential
source of great variation in all the tests presented here.  The following
precautions can help minimize this variation:
* Use only wood that has been thoroughly air dried.   For sticks 3 to 4
  cm in diameter drying time may be 3 to 8 months, depending on temperature,
  relative humidity, degree of protection from rain and
  mists, amount of air circulating through the wood pile, and wood
  species.   Hot water and steam escaping from the wood as it is burned
  are indications of very moist wood.
* Wood may be cut in a uniform size (3 x 3 cm, for example) and only
  this wood used for stove testing.  While this gives uniformity, it is
  often difficult to ignite and maintain a fire without smaller or
  tapered pieces.
  Alternatively, if a series of tests is planned, prepare in advance a
  stack of fuelwood to be used for each test.  Stacks should be as
  similar as possible in terms of wood type and size.  They should then
  be bound tightly to prevent loss of any pieces.  Sealing each wood
  stack in a large plastic bag will protect the wood from outside
6.  Temperature
Mercury thermometer are, in general, precise but breakable.  The glass
can break, and the liquid column can separate as well.   Spare glass
thermometers should be kept on hand.   Metallic thermometers are more
resistant but need periodic calibration, for example, by comparison
with a good quality glass thermometer.   Rechargeable battery-operated
thermistors and thermocouples have proven very useful in field work,
although models with digital readouts that are indistinct in direct
sunlight should be avoided.  In any case, look for instruments with a
long scale, as they give better resolution and precision.
Before using a thermometer for stove testing, check it in visibly
boiling water and look for a possible difference between the reading
and the normal boiling point for that altitude:
                                     altitude (meters)
        Actual boiling point = 100 - _________________
For Water Boiling Tests, simmering means that the water temperature is
kept no lower than 5 [degrees] C below the actual boiling temperature.  If water
temperature does drop below this point, the test should be discontinued.
7.  Volume
Volumes can be measured with graduated bottles.   One can also use commercial
bottles with known volumes (1/4, 1/3, 3/4, 1/1 liter).   A balance
can do the job, too, as 1 liter of water weighs 1 kg.
8.  Climatic conditions
Among the climatic data to be reported during stove testing, the most
important are: air temperature, wind conditions, and relative humidity.
* Air temperatures affects the rate of heat loss from stove and pots.
  It is also establishes initial water temperature in the Water Boiling
  Test.   Ideally, air temperature measurements should be taken before
  and after each test so that a mean value can be estimated.
* Wind conditions affect the stove's draft and can have considerable
  influence on stove performance.   Ideally, stove testing should be
  done only when conditions are calm.  Where this is not possible, a
  windbreak should be erected around the stove to reduce air movement.
* Relative humidity provides one indication of the moisture content of
  air-dried firewood (see Technical Note 3).  It is simple and useful
  condition to measure during stove testing.  For this purpose, a small
  sling psychrometer, a hair hygrometer, or a similar instrument is
  satisfactory.   Recalibrate a hygrometer frequently by wrapping it in
  a wet cloth, leaving it for five minutes, and adjusting it to 100
  percent RH.
9.  Pot and stove description
The test results are determined largely by dimensional relations
between the stove and the pot.   The internal dimensions of the stove
are especially important.  Therefore:
* Give a complete pot description (size, shape, weight, capacity,
  material, etc.).
* Give a functional stove description (inside dimensions, total
  weight, wall thickness, etc.).  Sketches should show at least the top
  view, cutaway side view with placement of pots, and a perspective.
  Drawings should be clearly labeled and all dimensions should be
10.  Ignition
For Water Boiling Tests and Controlled Cooking Tests it is important
to light the fire in the way it is normally done in the households of
the area.  For example, if kerosene (paraffin) is used as the ignition
material, three pieces of wood can be dipped vertically into kerosene
(about 8 cm deep) for about five seconds, and the excess kerosene
tapped off.  The kerosene-dipped wood should contain about 10 grams of
kerosene (check it by weighing the wood before and after dipping).  Or,
a measured amount of kerosene (less than 10 grams) may simply be
poured over the wood.  The test's starting time coincides with the
lighting of the kerosene-soaked wood pieces.   If desired, the kerosene
used may be considered as consumed fuel (1 gram of kerosene is equivalent
to about 2 grams of wood); however, the energy involved is so
small that it may safely be ignored in the calculations.
11.  Calculation of power
Power refers to the rate at which energy is used.   It may be expressed
as the amount of fuel used per unit of time (for example, 3 kg wood/hour,
or 50 grams/minute).  A widely used unit of power is the watt,
defined as one joule of energy per second.   (one gram of air-dry wood
yields about 20 joules).
Therefore, if a stoves consumes 300 grams of wood in 5 minutes you may
calculate the power level during that time as follows:
300 x 20 joules      6000 joules
______________   =   ___________    = 20 joules/sec = 20 watts
  5 x 60 seconds      300 seconds
12.  Statistical Analysis of Test Results
Any set of tests yields many measurements of a few well-defined parameters.
To get the maximum amount of information and insight about the
system being tested, it is useful to make a few relatively simple
statistical calculations.  In principle, these can be carried out on
all the tests described in these guidelines.   In practice, the Water
Boiling Tests and the Controlled Cooking Tests can be expected to be
performed under laboratory-like conditions by technically trained
personnel.  Variations in test results can generally be attributed to
either a faulty test design or deliberate changes introduced by the
tester on the system or its operating conditions.   Thus analysis of
results is simple.  However, the Kitchen Performance Test contains
several variables that are not under the control of the test designer
enter into the picture.  This is the place where the statistical analysis
becomes vital.
CONSUMPTION RATIO:  An expression sometimes used in the WBT with
multipot stoves.  It describes the amount of water evaporated from the
first pot relative to the water evaporated from all the pots on the
stove and is calculated by CR = [W.sub.1]/([W.sub.1] + [W.sub.2] + [W.sub.3] + ... + [W.sub.n]), where W
is the amount of water evaporated.
CONTROLLED COOKING TEST (CCT):   An intermediate laboratory test to
compare fuel and time used to prepare a meal on different stoves, and
to determine the range of meals a stove can accommodate in a given
area.  See page 11.
HIGH POWER:  Maximum stove power.  WBT high power phase brings the
water to boiling as rapidly as possible, and then maintains boiling at
the same heat level for 15 minutes.   See page 1.
KITCHEN PERFORMANCE TEST (KPT):   A field test to measure fuel consumption
in a normal household situation.   See page 19.
LOW POWER:  Minimum stove power.  WBT low power phase requires the fire
to be maintained at the lowest level necessary to simmer water for one
hour.  See page 1.
SPECIFIC FUEL CONSUMPTION (SFC):   An expression of the total amount of
food or water in the CCT or wet, divided by the total amount of wood
used to cook it.  See the Data and Calculation form on pages 7 and 15.
SPECIFIC DAILY CONSUMPTION (SDC):   An expression used in the KPT to
describe the amount of fuelwood (in kg) used for cooking per person
served per day.  See the KPT Data and Calculation Form on page 25.
STANDARD ADULT EQUIVALENT:  A standard way to define and compare the
number of people in a family group.   See Table I, page 22.
WATER BOILING TEST (WBT):  A simple laboratory test to measure the
fuel and time necessary to cook a simulated meal.   See page 1.
C    Celsius
CCT  Controlled Cooking Test
cm   centimeter
ISO  International Standards Organization
kg   kilogram
KPT  Kitchen Performance Test
kW   kilowatt
RH   relative humidity
SDC  Specific Day Consumption
SFC  Specific Fuel Consumption
WBT  Water Boiling Test
A.  Concepts of Efficiency
B.  Participants at Arlington Meeting
C.  Participants at Louvain "Woodstoves Seminar"
D.  Participants at Marseille Meeting
              Appendix A
There are many different ways of looking at stove performance and of
measuring stove efficiency.  A widely used method compares the energy
that goes into the stove with the energy that comes out, to determine
Percentage of Heat Utilized (PHU).   A broader concept of efficiency
accounts for energy losses in evaporation.   Once food reaches the boiling
point, the amount of additional heat it absorbs is relatively small.  In
water-based cooking the pot requires only enough heat to maintain boiling
temperatures--all else is excess.   This excess heat is used to generate
steam, which escapes from the pot without adding anything to the
cooked food.  Thus a stove that is regulated to maintain simmering temperature
with at least production of steam is, in that respect, most
efficient.  This section will review some different ways of measuring
1.  Energy losses
Figure 6 is an energy flow diagram for a woodburning

44p08.gif (600x600)

44p41.gif (600x600)

cook stove.  Useful heat is absorbed in the food, but
heat losses are associated with:
- incomplete combustion of wood
- heat loss from the stove body to the environment
- heat loss from the pot surfaces (including lids)
- heat loss through the chimney
- thermostatic steam escaping from the pot due to
  excessive stove power.
2.  Partial efficiencies
Different partial efficiencies can be suggested, for
* combustion efficiency
               heat generated by combustion
  [n.sub.c] =   ____________________________                                                                                              -          
               energy potential in fuelwood
          o heat transfer efficiency
                gross heat input to the pan
  [n.sub.t] =   ___________________________
                      heat generated

44p41.gif (437x437)

* pot efficiency
  [n.sub.p] =   net heat input to pot = gross heat input - surface losses
               _____________________   _________________________________
                 gross heat input              gross heat input
* control efficiency
  [n.sub.r] =   heat absorbed by the food
               net heat input to the pot
These efficiencies can be associated with stoves operated in predictable
or well-defined ways, such as at a single power level, or in defined
cooking patterns.
3.  Overall efficiency
An "overall stove efficiency" is often used.   This is a product of the
first three partial efficiencies described above.
  n' =        net heat input to pot
          ____________________________ = [n.sub.c] . [n.sub.t] . [n.sub.p]
          energy potential in fuelwood
A cooking efficiency can be defined as:
* [n.sub.c] =   heat absorbed by the food
               energy potential in fuelwood
This final efficiency level accounts for all the heat losses.  It is the
overall stove efficiency multiplied by control efficiency:
  n = [n.sub.c] . [n.sub.t . [n.sub.p] . [n.sub.r] = n' . [n.sub.r]
4.  Specific consumption
Alternatively, stove performance can be expressed by specific consumption
figures instead of efficiencies.   For example, at the cooking efficiency
         mass of consumed fuelwood
  SC =    _________________________              
           mass of cooked food
There is a link with the cooking efficiency, as
        heat absorbed in cooked food
  n =    ____________________________
        energy potential in fuelwood
  n =     (mass of cooked food) . c . [delta] t
        (mass of consumed wood) x heating va]ue
            1       c . [delta] t
Thus:  n = ___      _____________       
           SC       heating value
when c represents the weighted-mean specific heat of the food (4.184
kJ/kg), and [delta][t the temperature change (from ambient temperature to
boiling temperature).
        1        c     t
  SC =         _____________
        n      heating value
5.  Efficiencies in Water Boiling Tests
The overall stove efficiency can be measured in Water Boiling Tests by
heating the stove at high power, or by heating it at a controlled power
level where steam generation simulates absorbed heat.   A power-efficiency
plot can be drawn, with power limits [P.sub.min] - [P.sub.max].
Cooking efficiency can be measured in a similar way.   Note that in this
case the steam generation is a loss.   At simmering power levels the cooking
efficiency is close to zero.   The cooking efficiency concept therefore
has been applied to a cycle that includes both the heating up period
and simmering.  In this case, however, the cooking efficiency drops
as simmering times increase.
A better approach to this problem is to switch to specific consumption
      1        c. [delta] t = [delta] t .    c
SC =  __       ____________    _________    ___
      n        H.V.               n         H.V.
When the efficiency goes to zero during simmering, the SC figure will
not go to infinity (which is meaningless).   The reason for this is that
the temperature change [delta]t is also zero.
For practical reasons a Water Boiling Test report should give not only
the specific fuel consumption, but the power limits and evaporation as
well.  This will make it easier to predict cooking test results from
simple Water Boiling Tests.
Cooking efficiencies can more realistically be checked in Controlled
Cooking Tests.  Again, the concept should be applied to the entire cooking
cycle.  Note, however, that for the Controlled Cooking Test the
specific consumption is very dependent on the meal cooked, and can only
be used to compare two stoves that have cooked the same standard meal.
Table A-1 summarizes WBT data, and shows how data from WBT can be used
to judge stove performance in actual cooking tests.   The procedure
indicated is valid only for one-pot-hole stoves.   At the top of the table
are the WBT data from two different stove models.   Below that the WBT
data are applied to two imaginary cooking situations.   In the first test,
4 kg of food is heated to boiling, and then simmered for 90 minutes.  The
second test is the same except that the food is simmered only 15 minutes.
The quantity of food to be cooked is expressed as
                          W' = 4 kg
The expected water evaporation [W.sub.e] is computed from the evaporation rate
in the WBT, and the duration of the cooking test.   The initial food and
water used is
                          W' + [W.sub.e] = W
The time to boil is expected to be roughly proportional to the initial
food and water
                                                           initial food and water (CCT)
[(time to boil)] = [(time to boil).sub.wbt] X  ____________________________
                                                               initial water (WBT)
    *   The expected wood consumption is the sum of
       - wood to boil:  burning rate at [P.sub.max] x time to boil
       - wood to simmer:  burning rate at [P.sub.min] x simmer time
   * The expected specific consumption derives from
                       wood to boil + wood to simmer
                  SC = _____________________________
                       water vaporized, pot #1
The above approach gives an estimate--not a guarantee.   Wood consumption
might be higher than shown due to limited dynamic flexibility, poor
stove control, or other reasons.
                          Table A-1
Using Water Boiling Test results to calculate expected stove performance
in a Controlled Cooking Test.
WBT data:                        Stove 1                Stove 2
Power P                      2 - 4 kW                1 - 4 kW
                             (0.4 - 0.8 kg/h)        (0.2 - 0.8 kg/h)
(Pmax/Pmin                   2 kW                    3 kW
Initial water W'             5 kg                    5kg
Water left W'                4.05 kg                 4.68 kg
Evaporation We               0.95 kg/h               0.32 kg/h
Time to boil [t.sub.b]       20 min.                 30 min.
[SSC.sub.1]                  0.055                   0.080
[SSC.sub.2]                  0.167                   0.127
Cooking Test 1
(4 kg x 90 min simmer)
Cooked food W'              4 kg                     4 kg
Evaporated water We         0.95x90/60 = 1.43 kg     0.32x90/60 = 0.48
Initial food and water W    5.43 kg                  4.48 kg
Time to boil [t.sub.b]      5.43/5kgx20min = 22min   4.48/5x30 = 27 min
Wood:  to heat (kg)         (22/60)x0.8kg/h = 0.293  (27/60)x0.8kg/h = 0.360
Wood:  to simmer (kg)       (90/60)x0.4kg/h = 0.600   (90/60)x0.2kg/h = 0.300
                                              _____                     _____
                                              0.893                     0.660
Specific consumption        0.224                     0.165
Cooking Test 2
(4 kg x 90 min simmer)
Cooked food W'              4 kg                      4 kg
Evaporated water [W.sub.e]  0.95x90/60 = 1.43 kg      0.32x90/60 = 0.48
Initial food and water W    4.236 kg                  4.08 kg
Time to boil [t.sub.b]      4.236/5x20 = 17 min       4.08/5x30 = 24.5 min
Wood:  to heat (kg)         (17/60)x0.8kg/h = 0.225   (24.5/6)x0.8kg/h = 0.327
Wood:  to simmer (kg)       (15/60)x0.4kh/h = 0.100    (15/60)x0.2kg/h =   0.050
                                              _____                       _____
                                              0.325                       0.377
Specific consumption        0.081                     0.094
                            APPENDIX B
                 Participants at Arlington Meeting
Dr. Samuel Baldwin                   Mr. Hamata Ag Hantafaye
CILSS/VITA                           Laboratoire d'Energie Solaire
B.P. 3826                            B.P. 134
Ouagadougou, Upper Volta             Bamako, Mali
Prof. dr. ir. G. de Lepeleire        Mr. Stephen Joseph
Laboratorium voor Koeltechnik        Intermediate Technology Development
  en Klimaatregeling                  Group
Katholieke Universiteit              9 King Street
Leuven Celestijnenlaan 300           London WC2E 8HN
3030 Heverlee, Belgium               United Kingdom
Dr. Dhammika de Silva                Ms. Karen Kennedy
Wood and Cellulose Section           Aprovecho Institute
Ceylon Institute for                 442 Monroe Street
  Scientific and Industrial         Eugene, Oregon 97402 USA
P.O. Box 787                         Prof. dr. K. Krishna Prasad
363 Bauddhaloka Mawatha              University of Technology, W&S
Colombo 7, Sri Lanka                 P.O. Box 513
                                    5600 MB Eindhoven, The Netherlands
Dr. Gautam S. Dutt
Center for Energy and                Ing. Marco Augusto Recinos
  Environmental Studies             Proyecto Le a
Princeton, NJ 08544 USA              ICAITI
                                    Apartado Postal 1552
Mr. Howard Geller                    Avenida 1a Reforma 4-47, Zona 10
American Council for an              Guatemala, Guatemala, C.A.
  Energy-Efficient Economy
1001 Connecticut Ave., N.W.          Mr. Sylvain Strasfogel
Suite 530                            Association Bois de Feu/GRET
Washington, DC 20036 USA             73, Avenue Corot
                                    13013 Marseille, France
Dr. C.L. Gupta
TERI Field Research Unit             Dr. Timothy S. Wood
c/o Sri Aurobindo Ashram             VITA
Pondicherry 605002 India             1815 North Lynn Street
                                    Suite 200
                                    P.O. Box 12438
                                    Arlington, Virginia 22209-8438 USA
                            APPENDIX C
              Participants at Louvain "Woodstoves Seminar"
- Michel Christiaens
- G. de Lepeleire
  Laboratorium voor Koeltechniek en Klimaatregeling
  Katholieke Universiteit Leuven (Louvain)
  Celestijnenlaan 300A
  B-3030 Heverlee, Belgium
  Tel.:   016-23.49.31
- Beatrix Westhoff
- Franz Zinner
  Sozietat fur Enwicklungsplanung (SFE)
  Friedrichstrasse 38
  D-6000 Frankfurt am Main 1, West Germany
- Van der Spek Alexander
- P. Bussman
- K. Krishna Prasad
- Vermeer Nord-Jan
- C. Nieuwelt
- M. O. Sielcken
- P. Verhaart
- P. Visser
- P.T. Smulders
- S.F. Laperre
- N. Eossche
  Technische Hogeschool Eindhoven (THE)
  Postbus 513
  5600 MB Eindhoven, The Netherlands
  Tel:   47.38.30/47.21.47
- D.L.M. Baay
- Eric Ferguson
- W.F. Sulilatu
  Postbus 342
  7300 AH Apeldoorn, The Netherlands
- Robert Celaire
  GRET/GERES, 34 rue Dumont d'Urville, 75116 Paris France
  Tel:   502.10.10
  Centre St. Jer me
  13397 Marseille Cedex 13, France
  Tel:   98.90.10, ext 367, code 264
- P. Dunn
  Department of Mechanical Engineering
  University of Reading
  Reading RG6 2AH, United Kingdom
- H.E. Huynink
  Populierendreef 257
  2272 RE Voorburg
  The Netherlands
- Yvonne Shanahan
- Stephen Joseph
  ITDG Power Unit
  A.R.S. Shinfield
  University of Reading
  Reading RG6 2AH, United Kingdom
- Waclaw L. Micuta
  Bellerive Foundation
  5, rue du Vidollet
  CH-1202 Geneva, Switzerland
  Telex:   427993, tel:   (22)33.74.22
- Rainer Geppert
- Cornelia Sepp
  GTZ GmbH
  Deutsche Gesellschaft fur Technische Zusammenarbeit
  Postfach 5180
  Dag-Hammerskjoldweg 1
  D-6236 Eschborn 1, West Germany
- Peter Pluschke
  GATE (German Appropriate Technology Exchange)
  Postfach 5180
  D-6236 Eschborn 1, West Germany
- Gunter Salzmann
  Friedrichstrasse 38
  D-6000 Frankfurt/Main
- Ianto Evans
  Aprovecho Institute
  442 Monroe Street
  Eugene, Oregon 97402 USA
  Tel:   503/683-2776
- Robert Chom
- Anne Spirlet
- Michel Taymans
  Agence Internationale du D veloppement Rural (AIDR)
  Handelsstraat 20
  B-1040 Brussels, Belgium
- Alice Guidicelli
  CEE-D veloppement/Energie
  Berlament 995
  B-1049 Brussels, Belgium
  Tel:   02/735.00.40, ext. 3771
- J.A. Boer
  Ministry Foreign Affairs
  Muzensstraat 30
  The Hague, The Netherlands
- Dr. Timothy Wood
  1815 North Lynn Street, Suite 200
  P.O. BOx 12438
  Arlington, Virginia 22209-8438 USA
  Tel:   (703) 276-1800
- Bernard Kauffmann
  145, rue St. Dominique
  75007 Paris, France
  Tel:   705.16.29
- Louis Vroonen
  ABGS (Ministry of Developing Countries)
  Maraveldplein 5
  1050 Brussels, Belgium
- Sylvain Strasfogel
  Association Bois de Feu/GRET
  73, avenue Corot
  13013 Marseille, France
  Tel:   (91) 70.92.93
- J.B. Roggeman
  Club du Sahel
  13-15 Chaus e de la Muette
  75016 Paris, France
- Vera Van Eenoo
  Zeeptstraat 50
  B-2850 Keerbergen, Belgium
- Donaat Cosaert
- Chris Avondts
  Plijde Inkomststrzat 9
  B-3000 Louvain, Belgium
- Luc Vandaele
  Werkgroep Zachte Technologie
  St. Janshuis
  B-3030 Heverlee, Belgium
- Joseph Melotte
  Zandheuvel 1, Appt. 123
  B-8401 Bredene, Belgium
                              APPENDIX D
             Participants at Marseille meeting, 12 - 14 May 1982
Beatrix Westhoff
Sozietat fur Enwicklungsplanung (SFE)
Friedrichstrasse 38,
6000 Frankfort, West Germany
Elisabeth Gern
Karen Kennedy
Aprovecho Institute
442 Monroe St.
Eugene, Oregon 97402 USA
Ralph Royer
Church World Service
B.P. 11624
Niamey, Niger
Michel Taymans
Agence Internationale du D veloppement Rural (AIDR)
20, rue du Commerce
B-1040 Brussells, Belgium
Beauchesne Patrick
45 bis Bd. Belle Gabrielle
94130 Nogeret/Marne, France
Annette Legris
5, av. Porte Braucion
75015 Paris, France
Patrick Hauser
16, rue des Samfoins
77380 Combe la Ville, France
Bernard Kauffmann
145, rue St. Dominique
75007 Paris, France
Pedro Costez
Apartado postal 159
Quetzaltenango, Guatemala, C.A.
Roberto Caceres
Apartado Postal 1552
Avenida la Reforma 4-47, Zona 10
Guatemala, Guatemala, C.A.
Malcolm Lillywhite
Box 2043
Philippe Simonis
Postfach 5180
Eschborn 1, West Germany
Yvonne Shanahan
Stephen Joseph
A.R.S. Shinfield
University of Reading
Reading RG6 2AH, United Kingdom
Sylvain Strasfogel
Association Bois de Feu/GRET
73, avenue Corot
13013 Marseille, France
G. de Lepeleire
Katholieke Universiteit Leuven
Waversebaan 178
B-3030 Heverlee, Belgium
Woodstove Group
Technische Hogeschool Eindhoven (THE)
Postbus 513
5600 MB Eindhoven, The Netherlands
Mr. W.J. Weerakoon
University of Zambia
P.O. Box 32379
Lusaka, Zambia
Mme. Seck
B.P. 476
Dakar, Senegal
E. Ferguson
van Dormaalstraat 15
Eindhoven, The Netherlands
Alice Guidicelle
200, rue de la Loi
B-1049 Brussels, Belgium
Cherif Zaouch
4040 Tunisie
L. Van Daele
Holsbeeksesteenweg 117
B-3200 Keseel-Lo, Belgium
Faculty of Engineering
Chulalongkorn University
Bangkok 5, Thailand
Tata Research Institute
Bombay House
24, Homi Mody Street
Bombay 400023, India